DMREF/Collaborative Research: Designing and Synthesizing Nano-Metallic Materials with Superior Properties

通常，限制车辆、发电机、土木工程结构和许多其他产品性能的主要因素是它们所用金属的耐用性。因此，更好的金属是推动技术进步的关键，这些技术是美国竞争力和安全的核心：交通、能源和基础设施。纳米金属材料包括一类有望满足这一需求的金属：它们具有极高的强度，抗重复加载造成的损伤，以及许多独特的性能，如抗辐射损伤。这项研究项目解决了纳米金属材料到目前为止限制其实际使用的一个缺陷。也就是说，当它们伸展时，它们并不是均匀地贯穿全身，而是在孤立的位置被掐断。该项目将创造出拉伸均匀的纳米金属材料，因此不容易突然失效。因此，它将消除纳米金属材料广泛技术使用的一个主要障碍，并加快其在市场上的部署。该项目还将向高中教师和学生、妇女、来自代表性不足的少数族裔的个人以及更广泛的科学界开展外联活动。尽管许多纳米金属材料具有内在的延展性，但它们似乎以脆性的方式失效，因为它们的塑性变形局限于狭窄的区域，随后断裂。该项目的目标是通过理论、建模和实验相结合的迭代设计过程来设计纳米金属材料的结构、界面/表面和组成，从而创建抗流动局部化的纳米金属材料。该项目将遵循迭代设计-综合-测试周期，快速扫描设计空间，并通过更新将设计参数与性能指标联系起来的理论模型来整合在每次迭代中获得的见解。由于纳米金属材料的纳米级微结构尺寸，传统的基于位错的机制不适用于避免流动局部化。因此，该项目将探索和实施非位错机制，这些机制依赖于孪晶、表面和界面应力、凝聚力、界面滑移障碍、约束层滑移以及流动局部化和均匀变形成分的复合材料。

Often, the main factor limiting the performance of vehicles, power generators, civil engineering structures, and many other products is the durability of the metals they are made of. Better metals are therefore key to advancing technologies at the core of US competitiveness and security: transportation, energy, and infrastructure. Nano-metallic materials comprise a class of metals that promise to fill this need: they possess extreme strength, resistance to damage from repeated loading, and numerous unique properties such as resistance to radiation damage. This research project addresses a drawback of nano-metallic materials that has so far limited their practical use. Namely: when they stretch, they do not elongate uniformly throughout, but rather pinch off in isolated locations. This project will create nano-metallic materials that stretch uniformly and are therefore not prone to sudden failures. It will thereby remove a major impediment to the widespread technical use of nano-metallic materials and accelerate their deployment to the marketplace. This project will also undertake outreach activities to high school teachers and students, women, individuals from underrepresented minorities, and the broader scientific community.Even though many nano-metallic materials are intrinsically ductile, they appear to fail in a brittle-like manner because plastic deformation in them localizes into narrow zones that subsequently fracture. The goal of this project is to create nano-metallic materials that resist flow localization by engineering their architectures, interfaces/surfaces, and compositions via an iterative design process that integrates theory, modeling, and experiments. The project will follow an iterative design-synthesize-test cycle that scans the design space rapidly and integrates insights gained in each iteration by updating theoretical models connecting design parameters to performance metrics. Due to the nanometer-scale microstructure dimensions in nano-metallic materials, conventional dislocation-based mechanisms for averting flow localization are not applicable. Therefore, this project will explore and implement non-dislocation mechanisms that rely on twinning, surface and interface stresses, coherency stresses, interface barriers to slip, confined layer slip, and composites of flow-localizing and uniformly deforming constituents.